As cellular telephone service has increased, a need has arisen for a single telephony system that can service a subscriber both at his home, that is, fixed-base, or stationary, and when he is away from home, or mobile.
U.S. Pat. Nos. 5,412,760 and 5,528,665, issued to Peitz, describe a telephone system for both mobile and stationary subscribers, in which the stationary subscribers are not assigned permanent channel pairs, but rather are treated as the mobile subscribers, and are assigned channel pairs at the time a telephone connection is made. All connection channel pairs are within the frequency spectrum of the broad band cable connecting the stationary subscribers.
However, the Peitz patents do not contemplate using unshielded copper pair telephone lines normally used for ISDN basic rate service. Rather, they teach installing new digital, preferably fiber optic, cables to subscribers' homes.
Analog cellular telephone service originally developed independently in various countries, each country's equipment and service incompatible with the others'. The Europeans eventually agreed on standards for digital cellular telephone service, called "GSM" ("Global System For Mobile Communications"). The European Telecommunication Standards Institute (ETSI) published phase I of the GSM specifications in 1990. ETSI published some GSM Technical Specifications, version 5.1.0, in March, 1996.
A need exists for a single telephone system for both mobile and stationary subscribers, which uses unshielded copper pair telephone lines normally used for ISDN basic rate service, and which is compatible with the GSM standards.